We studied reflectance spectra collected in vitro and in vivo from different sites in urinary bladder by means of a model, similar to one used in colonic studies. The model takes into account propagation of light in presence of oxy- and de-oxy- hemoglobin and scattering on collagen fibers and provides parameters that characterize hemoglobin concentration and average scatterer size for dysplastic and non-dysplastic tissues.